Brad Hamilton is a popular senior who is looking forward to his last year of school and almost has his 1960 Buick LeSabre paid off. He has a part-time job at All-American Burger, where his girlfriend, Lisa, also works. Brad is subsequently fired for losing his temper at an obnoxious customer. When Brad tries to tell Lisa how much he needs her, she says she is breaking up with him to see other guys. Brad quits his job at Captain Hook Fish & Chips because of the humiliation of having to wear a pirate costume when delivering food.
Brad’s sister Stacy is a 15-year-old sophomore and also a virgin. Stacy works at a pizza parlor at the mall alongside her outspoken friend, popular and sexually active Linda. One night at work, Stacy takes an order from Ron Johnson, a 26-year-old stereo salesman who asks her out after she tells him she’s 19. She then sneaks out to meet him and have sex in a dugout at a softball field. Stacy never hears from Ron again, revealing the loss of her virginity to Linda.
Mike Damone, a dilettante who earns money taking bets and scalping tickets, fancies himself a sagacious and worldly ladies’ man. After Mike’s friend Mark Ratner proclaims his love for Stacy to him, Mike lets Mark in on his five secrets for picking up girls. Mike later coaxes Mark into taking Stacy on a date to a German restaurant. Afterwards, at her home, Stacy invites Mark into her bedroom, where they look at Stacy’s photo album together. They eventually kiss, but he soon shies away and leaves after Stacy attempts to become intimate with him. Stacy invites Damone over after school for a swim in the pool, which leads to them having sex in the pool house. Stacy later informs Damone that she is pregnant, and tells him she’s scheduled an abortion. But on the day of her appointment, embarrassed at being unable to raise the money for his half of the bill, Damone ignores her. Stacy asks Brad to drive her to a bowling alley, but she goes to the abortion clinic across the street. When Brad returns, Stacy makes him promise not to tell their parents. When Stacy tells Linda, Linda becomes angry at Damone, leading to an almost physical confrontation between Damone and Mark in the boys’ locker room until it is broken up by the gym teacher.